brightcove.createExperiences(); It looks like Rob Kardashian and Blac Chyna’s relationship is progressing even further.

Rob, 28, was spotted outside Blac Chyna’s gated community in Los Angeles this week, and a source tells PEOPLE that he is now staying in her home after living with sister Khloé Kardashian for years.

“The drama continues. Rob still has some of his things at Khloé’s house. He hasn’t arranged to pick it up,” the insider says. “Khloé knows that he is living with Blac Chyna. Khloé feels very betrayed. She always stood up for Rob and defended him. She has gone out of her way a million times to help him. She is very frustrated at the lack of respect for his family.”

On Monday, source confirmed to PEOPLE that Rob and Blac Chyna “are dating and have been for a few weeks.” (They sparked romance rumors Monday when Blac Chyna, 27, posted a picture of herself with Kardashian’s arm around her, and he then followed up with a meme of Blac Chyna preparing to give birth to a “baby Kardashian.”)

Over the past two years, Rob has battled depression and significant weight gain, and most recently was diagnosed with diabetes. Though the source said it’s unclear “how serious it is” between Rob and Blac Chyna, he has “found an escape from his family nagging him about his health” and has “ignored their attempts to contact him.”

“Rob has been lonely for so long, so of course it’s great for him to spend time with someone other than his sisters,” the source said. “Rob likes her and seems to think it’s mutual. It’s just hard to take things seriously since obviously both share a lot of anger toward the [Kardashian-Jenner] girls. They have both had a lot of drama with Kim. Rob really seems to get a kick out of all the drama that he is causing.”

Indeed, Blac Chyna has a long and tumultuous history with the Kardashian/Jenner family. Though she was previously pals with the famous reality stars (she even attended Kendall Jenner‘s 18th birthday at Six Flags Magic Mountain in 2013), the relationships went south after her ex-fiancé (and father of her child), rapper Tyga, now 26, started dating Kylie Jenner, now 18.

From left: Blac Chyna, Rob Kardashian and Kim Kardashian at Six Flags in 2013

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“Kylie is livid,” a source told PEOPLE on Monday. “She feels super betrayed and can’t understand why someone in her own family would stab her in the back like that.”